Submarine coaxial cables

ABSTRACT

There is provided a submarine coaxial cable in which both of the inner and outer conductors or at least the inner conductor, is made of a conductive material having a lower temperaturecoefficient of resistivity than that of annealed pure copper. The change of attenuation with respect to the temperature of the submarine coaxial cable may be considerably decreased.

United States Patent [191 Kumagai et a1.

[ SUBMARINE COAXIAL CABLES [75] Inventors: Denroku Kumagai, Tokyo; Gen

Marubayashi, Mito; Kishio Arita, Mito; Shugo Kubo, Mito; Goro Yamauchi,Mito; 'Toshio Takahashi, Mito; Toshihiko Sato, Tokyo, all of Japan {73]Assignee: Nippon Telegraph and Telephone Public Corporation, Tokyo,Japan 22 Filed: Aug. 7, 1973 21 Appl. No; 386,284

[30] Foreign Application Priority Data v Aug. 8, 1972 Japan 47-79241Sept. 1, 1972 Japan.... 47-87624 Sept. 1, 1972 Japan.... 47-87625 Sept.1, 1972 Japan.... 47-87626 Sept. 1, 1972 Japan 47-87627 [52] US. Cl.174/102 R, 174/107, 174/126 R, 174/128 [451 Feb. 11,1975

51 int. Cl. 1101b 7/18 [58] Field of Search 174/102 R, 102 A, 107,174/126 R, 126 CP, 128; 333/96, 81 A, 97 S; 178/45 [56] References CitedUNITED STATES PATENTS 2,337,556 12/1943 Hosking: 174/102 A 2,831,9214/1958 Morgan 333/96 X 2,924,795 2/1960 Black et al 333/96 2,929,0343/1960 Doherty 333/96 X 3,569,610 3/1971 Garner et a1. 174/102 R PrimaryExaminer-Arthur T. Grimley [57] ABSTRACT There is provided a submarinecoaxial cablein which both of the inner and outer conductors or at leastthe inner conductor, is made of a conductive material having a lowertemperature-coefficient of resistivity than that of annealed purecopper. The change of attenuation with respect to the temperature of thesubmarine coaxial cable may be considerably decreased.

12 Claims, 9 Drawing Figures ATENIEmIBnim-s v 3.865 971 SHEET 10F 8INSULATOR FIG 2 ATTENUYATION (db e 5 lb 5b lo'o FREQUENCY(MH2) THE GRAPHILLUSTRATING THE RELATION BETWEEN THE FREQUENCY AND THE AT' TENUATION OFTHE SUBMARINE CABLE.

Z /XTENTEU FEB] 1 IQYS sum 2 or s FIG. 3

A: MATTHIESSEN'S RULE b-f CONDUCTIVE MATERIALS OF THE INVENTION O Y O 4L/ll TEMPERATURE-COEFFICIENT OF RESISTIVITY (I/C) THE GRAPH ILLUSTRATINGTHE RELATION BETWEEN MATHIESSEN'S'RULE AND THE ELECTRICAL PROPER- TIESOF THE CONDUCTIVE MATERISLS PATENTEDFEBHIQTS 3865,97].

SHEET 3 OF 8 FIG. 4

o PURE COPPER b 3 0.2% THERMISTOR CU ELECTRICAL RESIST-IVITY LSl-Cm) I II I -20 0 20 4b 60 so TEMPERATURE(C) THE GRAPH ILLUSTRATING THE CHANGEOF RESISTIVITY WITH TEMPERATURE OF THE CONDUCTIVE MATERIAL (0.2%THERMISTOR-Cu) I T'fCENTEU T551 71975 SHEET u 0F 8 FIG. 5

O: PURE COPPER b 0.2% FERRlTE-CU EOEO 22. .l

TEMPERATURE (c) THE GRAPH ILLUSTRATING THE CHANG WITH TEMPERATURE OF THECON (0.2% FERRlTE-CU) E OF RESISTIVITY DUCTIVE MATERIAL PMMEU E 1865971SHEET 5 OF 8 'g. O1 PURE COPPER b 0.2% MgO -Cu 3 I *1 2 2.0- U) 6 i I5-E |.0- l-v 0 LL! l LLl l l l 1 -26 0. 2b 40 6O 8O TEMPERATURE (c THEGRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY WITH TEMPERATURE OF THECONDUCTIVE MATERIAL 0.2% MgO-Cu) I WEE TEflFEBH-IBYS SHEET 6 OF 8 FIG. 7

0 RuRE COPPER b 0.5% TiC-Cu EQ QE E ERE 3258 5 TEMPERATURE (C) THE GRAPHILLUSTRATING THE CHANGE OF RESISTIVITY WITH TEMPERATURE OF THECONDUCTIVE MATER IAL (0.5 TiC-Cu) mam FEB] 1 I975 sum 70F a FIG. 8

ELECTRICAL RESISTIVITY m-cm) I I I l -2o 0 2fo -40 6O 8O TEMPERATURE(C)THE GRAPH ILLUSTRATING THE CHANGE OF RESISTIVITY P/Vlglj INEMPERATURE OFTHE CONDUCTIVE MATERIAL I. o i-Cu -CU) P/IIEIITEU FEBI I I975 sum 8 OF 8FIG. 9

- FREQUENCY (MHZ m m O O O O X THE GRAPH ILLUSTRATING THE RELATIONBETWEEN THE FREQUENCY ANDTHEATTENUATION OF THE CABLE IN ACCORDANCE WITHTHE INVENTION BACKGROUND OF THE INVENTION The present invention relatesto a submarinecoaxial cable in which an inner conductor or both innerand outer conductors are made of a conductive material having a lowtemperature-coefficient of resistivity.

Shallow sea cable transmission systems have been recently watched withmuch interest because the cable laying speed is faster, the cablemanufacturing cost is less expensive and the operation is more reliablethan land cable system. However the problem is that the repeaters aremore expensive than those used in the land cable system. Especially whenthe transmission band is higher than 10 MHz, the repeaters must beinserted every 10 odd kilometers, so that the cost of the repeatersbecomes the major cost of the shallow-sea cable system. Therefore, theproblem is the research and development of repeaters which areinexpensive to manufacture yet reliable in operation. However, at thecontinental shelf up to 200 meters in depth, the temperature of seawater changes from one place to another and according to the season. Theconductors of the-communication cables are generally made of pure copperwhose temperature coefficient of electrical resistivity (dp/dT) isfor'very high-and is example, 6.77 X luQ-cm/"C at 30C so that the rateof change of electrical resistivity p with temperature is very high.Therefore, the change of attenuation with temperature must be taken intoconsideration in a shallow sea cable system. That is, the changeof=attenuation with temperature must be equalized by some means and somemargin oferror must be takeninto consideration in the design of therepeaters in order to prevent an overload and the noise decay. As aresult, the cost of repeaters is increased.

In order to overcome this problem, there has been proposed and used amethod for inserting an automatic gain control (AGC) circuit into arepeater for a submarine coaxial cable system. In a typical automaticgain control circuit, the temperature of the sea water is detected by adirect-heating type thermistor so that the response of an equalizingcircuit may be controlled in response to the change in resistance of thethermistor. This method has an advantage in that the circuit is simplein construction, but also has a disadvantage in that the response erroris very high. In order to reduce the residual error there has beenproposed a method for utilizing an automatic gain control circuit with apilot control; but the system is complicated and the repeaters becomeexpensive to manufacture and are unreliable in operation.

In view of the above, one of the objects of the present invention is toprovide a submarine coaxial cable whose change of attenuation withtemperature is extremely small.

Another object of the present invention is to provide a submarinecoaxial cable which itself functions as a circuit equivalent to anautomatic gain control circuit so that the submarine coaxial cable maybecome inexpensive to manufacture but is highly reliable in operation. I

Another object of the present invention is to provide a submarinecoaxial cable using conductors made of a novel dispersion-typeconductive material with a low temperature-coefficient of resistivity sothat the temperature coefficient of loss of inner dielectrics may becompensated, with theresulting considerable reduction in the changeofattenuation with temperature of the submarine cable.

The present invention willbecome more apparent BRIEF DESCRIPTION OF THE-DRAWING FIG. 1 is a cross sectional view of a typical submarine coaxialcable;

FIG. 2 is a graph illustratingthe relation betweenthe frequency and theattenuationof a submarine cable, the graph being used for anexplanationlof the underlying principle of the present invention;v

FIG. 3' is a graphused'for the explanation of the'relation betweenM'atthiessens rule and. the electrical properties of the conductivematerialsin accordance with the present invention;

FIGS. 4-8 are graphs illustrating the changes of resistivity withtemperature of the conductive materials prepared in accordance with thepresent invention in comparison with that of pure copper (curvea);

FIG. 9 is a graph illustrating the changes of attenuation withtemperature of the cables in accordance with the present invention usingthe conductors made of a conductive material consisting of 0.15% Al O Cuprepared in accordance with the present invention in comparison withthose of the conventional cables using the conductors made of copperwires; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 a submarinecoaxial cable is gen erally composed of a steel strand. 1 covered with afirst copper tape 2 which serves as an inner-conductor, a second coppertape 4 which is coaxially spaced apart from the first copper tape 2andserves as an outer conan fiu v pJdn/rn z/ 1)] N /m 3 a8 K VEIftanSNep/m 4 d d outer diameters of inner conductor and insulation in meters,

p p resistivities in ohm-meter of inner and outer conductors,

e, relative dielectric constant of insulator 3 filled into the spacebetween the inner and outer conductors,

tan8 dielectric power factor of the insulator 3,

f= frequency in Hz,

K, coefficient equals 5.27 X 10 and K coefficient equals 1.05 X 10 Whenthe temperature of the coaxial cable changes from TC to (T AT)C, theabove parameters change as follows: 7

d, z constant 1 v 5 tanfi (T+ AT) tan6(T) {l K 'AT} Since the linearthermal expansion coefficent of the Next, the underlying principle ofthe present invention will be described with reference to FIG. 2. Thecurve d indicates the change in attenuation when a conductive materialwith a low temperature coefficient inner conductor is negligibly small,d is constant as 5 is used so that the change in attenuation due tochange shown in Eq. 5, and temperature coefficients K K e in resistivityis decreased from the curve a tothe curve and K 5 are negative whereas Kp l and K p 2 are posa. It can be seen that this method is veryeffective to itive. decrease the overall change in attenuation of thecable.

Due to the temperature variations of these parame- In the instantembodiment, the temperature coeffiters, there are attenuation changeswith temperature as l0 cients of the conductors were reduced by aboutpcrshown in Table 1. cent with the result of the reduction in change inatten- Table l alternation frequency variation characterattenuationsymin response to istics of in Nep or dB causes bol temperature riseattenuation in proporchange of tion to 1/2K p ,a AT resistivity f ofinner conductor increase a change of do. f" VzK p 2(MAT resistivity ofouter conductor change of do. f /2K 5 (a,,+a,,)AT dielectric constantdecrease b change of do. f K,,{a, +(a, +a,,/ln(d /d,)} diameter of outerconductor change of do. f'-" AK g a 6 AT dielectric constant decrease cchange of do. f""' K 5 a 5 AT tanS The terms in proportion to f areintroduced beuation to about one third. FIG. 2 shows that when the causethe frequency characteristic of dielectric power temperature coefficientof the conductors are defactor of the insulator, which is generallypolyethylene, 40 creased from the curve a to the curve a the change inis in proportion to P at a low frequency less than 500 attenuation isconsiderably reduced as shown by the MHz. Changes in diameter of theouter conductor are arrow d to d. Ordinarily the change in resistivityof the caused by the volume expansion of the insulator. conductor withtemperature, which is the main cause When the conductors are made ofannealed pure of the change in attenuation, is compensated to somecopper and the insulators are made of polyethylene, the extent by thechange with temperature of the insulator, temperature coefficients areas follows: so that the change in attenuation with temperature may K p Kp 2 3.9 X l0"/C be considerably reduced when the temperature coeffi- K e4.9 X l0"'/C cient of resistivity of the conductor is slightly reduced.K,, 2.9 X lO"/C The curve d in FIG. 2 indicates the case where both K 5-5.7 X lO' /C the inner and outer conductors 2 and 4 of the coaxial Therelation of the above variation factors with the cable shown in FIG. 1were made of a material with a overall variation is shown in FIG. 2 whenthe outer conlow temperature coefficient of resistivity. However, inductor is 25.4 mm in inner diameter and the inner conpractice, thechange in attenuation with temperature ductor is 8.38 mm in diameter.The frequency change may be satisfactorily reduced only by making theinner per 1C of the submarine coaxial cable of I kilometer conductor 2of a material with a low temperature coefis shown, and a, b and c inFIG. 2 show the parameters ficient of resistivity. Shown in Table 1.Next, the conductive materials for the inner and The change ofattenuation is given by a (b c) outer conductors of the coaxial cable ofthe present ina. It is seen that the change in attenuation is suddenlyvention will be described. In FIG. 3 the curve A indidecreased at a highfrequency mainly because of the cates the Matthiessens rule. It is seenthat the product effect of tan 8 (the curve d), but is considerably highof the resistivity (p) of a conductor (including copper at a lowfrequency because of the lesser effect of tan8. alloy) and thetemperature coefficient l/p)'(dp/d!)] In view of the above, the primaryobject of the presis a constant so that the resistivity is increased asthe ent invention is to considerably decrease the change in temperaturecoefficient of resistivity is decreased. attenuation with temperature ofa submarine coaxial Therefore, in the conventional coaxial cables usingthe cable by using a conductive material with a low temperaturecoefficient of electrical resistivity.

inner and outer conductors made of copper alloys, it is difficult toreduce the temperature coefficient of resistivity without increasing theattenuation even when a conductive material with a low temperaturecoefficient of resistivity is used. However, in case of the conductivematerials in which a small percentage of one of the metal oxides,ferrite, finely divided thermistor, carbides, or finely dividednickel-copper alloy powder is dispersed into copper, Matthiessens ruleis not valid so that the temperature coefficient of resistivity may bereduced by about 30 percent without increasing resistivity. In FIG. 3, awhite dot a indicates the measured value of a standard annealed copperwire; a white triangle b, a copper wire into which is dispersed 0.2percent of thermistor fine powder; c, a copper wire into which isdispersed 0.2 percent of MgO; d, a copper wire into which is dispersed0.15 percent of A1 e, a copper wire into which is dispersed 0.5 percentof finely divided TiC', and f, a copper wire into which is dispersed 1.0percent of nickel-copper alloy powder. Electrical properties of theseconductive materials are shown in In addition to the above conductivematerials, there maybe used ferrite such as MnCoFe O BaFe O NiZnFe ONiCuFe O Li ,-,Fe O and the like; thermistor powder consisting of, as amajor component, oxides of transition metal elements, that is the oxidesof Mn, Ni, Co and Cu, and, as a minor component, the oxides of Mo, Fe,Cr, and V; oxides such asMgO, A1 0 Mn O CrO V0 V 0 ThO and the like; andcarbides such as Mo C, SiC, TaC, WC, Fe C and the like. In general, 0.015.00 percent by weight of these compounds are added to copper to obtaina desired temperature coefficient of resistivity. In addition to theabove compounds, 0.01 5.00 percent by weight of, Ni-Cu alloy may beadded to copper. However, when the weight ofa compound to be added isless than 0.01 percent, a desired low temperature coefficient is notobtained, and when the weight is in excess of 5.0 percent, a conductivematerial becomes too brittle to be drawn or rolled even though asatisfactory low temperature coefficient of resistivity is obtained.Next, some examples of the present invention will be described.

EXAMPLE 1 40 percent by weight of Mn0 35 percent by weight of C00, 20percent by weight of NiO and 4 percent by weight of CuO 50 grams of purecopper powder of about 100 microns in particle size and 50 grams ofthermistor fine powder about 40 microns in particle size were uniformlymixed in ethyl alcohol, and thereafter eter. The wire was annealed forabout 1 hour at 600C in vacuum, and then cooled in the furnace. Thecontent of thermistor powder in the wire was 0.2 percent. The thermistoroxide was uniformly dispersed in copper matrix. The resistivity wasmeasured by an automatic electrical resistance measuring equipment at lX 10' torr at a speed of 0.625C/minute.

EXAMPLE 2 FIG. 5 shows the change of resistivity with temperature (curveb) of a copper wire having 0.2 percent of ferrite dispersed therein incomparison with that of a pure copper wire. 99.8 grams of pure copperpowder 10 microns in particle size and 0.2 grams of MnCoFe- 0 500A inparticle size' was uniformly mixed in ethyl alcohol, and thereafter thealcohol was evaporated at 50C. The mixture was pressed by a rubber pressmachine under a hydrostatic pressure of 3,000 kg/cm and then sintered invacuum for 2 hours at 950C. The pressed material was forged at 850C anddrawn into a wire 0.7 mm in diameter. The wire was annealed for about 1hour at 600C in vacuum and then cooled in the furnace. Ferrite wasuniformly dispersed in copper matrix which was confirmed by an imageanalyzer in a quantitative metallurgical system.

Co-precipitation of MnCoFe O was effected by reaction in aqueoussolution and then synthesized by hydrothermal synthesis. The particlesize'of MnCOF 0 was confirmed by an electron microscope. in like manner,other ferrites such as BaFe O NiZnFe O,, NiCuFe O and Li Fe O were used,and the electrical properties of copper wires thus provided are shown inTable 3.

Table 3 FIG. 6 shows the change of resistivity with temperature (curve bofa copper wire containing 0.2 percent of MgO in comparison with thecurve a of a pure copper wire.

50 grams of pure copper powder about microns in particle size and 50grams of MgO about 10 microns in particle size were mixed methylalcohol, and then the alcohol was evaporated at 50C. The mixture waspressed into a cylinder by a mechanical press under a pressure of 1,000kglcm The mold was sintered for about 1 hour at 800C to provide a Cu-MgOmother al- 10y. 1.6 grams of the mother alloy was added to 200 grams ofmolten copper at 1,250C and mixed for I about hours before it was castin a mold. The yield of MgO in the mother alloy was about 50 percent,and the copper alloy contained 0.2 percent of MgO. The ingot was forgedat 850C, drawn into a wire 0.7 mm in diameter, annealed in vacuum at600C for about 1 hour and then cooled in the furnace. The added MgO wasuniformly dispersed in a copper matrix, and the change of resistivitywith temperature was measured by an automatic electrical resistancemeasuring equipment at 1 X 10 torr and at a speed of 0.625C/minute.

In like manner, 99.5 grams of pure copper powder 10 microns in particlesize and 0.5 grams of Th0; powder 0.7 microns in particle size wereuniformly mixed in ethyl alcohol, and thereafter the alcohol wasevaporated at 50C. The mixture was pressed by use ofa rubber pressmachine under a pressure of 3,000 kg/cm 50 grams of pure copper powder100 microns inparticle size and 50 grams of TiC'4O microns in particlesize were uniformly mixed in ethyl alcohol and thereafter the alcoholwas evaporated at 50C. The mixture was pressed into a cylinder by amechanical press under a pressure of 1,000 kg/cm and the cylinder wassintered for one hour at 800C to prepare a Cu-TiC mother alloy. 2.0grams of the mother alloy was charged into 98 grams of molten copper atabout 1,250C and mixed for 10 minutes before it'was cast into a metalmould. The yield of TiC in the mother alloy was about 50 percent, andthe ingot contained 0.5 percent of TiC. The ingot was forged at 850 C,drawn into a wire of 0.7 mm in diameter, annealed for about 1 hour at600C in vacuum, and then cooled in the furnace. The-change ofresistivity-with temperature was 7 measured by an automatic electricalresistivity measuring equipment at 1 X 10 torr and at a speed of0.625C/minute.

Table 5 shows the electrical properties of copper wires containingcarbide powder.

Table 5 uQ-cm/C pure 7 copper pure copper 1.79 3.78 6.77 100 0.5% TiC-Cu1.792 2.86 5.13 75.8

1.5% TiC-Cu 1.870 3.02 5.65 83.5

0.3% WC-Cu 1.904 2.93 5.58 82.4

firmed by an image analyzer in a quantitative metall'ur- EXAMPLE 5 gicalsystem that ThO was uniformly dispersed in copper matrix.

ln like manner the copper wires containing other oxides such as MnO CrO'V0 and V 0 were prepared, and the electrical properties of the copperwires of Example 3 were shown in Table 4.

FIG. 7 shows the change of resistivity with temperature (curve b) of acopper wire having-0.5 percent of TiC dispersed therein in comparisonwith-that ofa pure copper wire (curve a).

FIG. 8 shows the change of resistivity with temperature (curve b) of acopper wire containing 1' percent of (50% Ni-Cu).alloy in comparison.with that of a pure copper (curve a). t

. 198 grams of pure copper powder about microns in particle size and.2.0 grams of 50% Ni-Cu) alloy about 40 microns in particle size wereuniformly mixed in ethyl alcohol. (50% Ni-Cu) alloy was prepared by anatomization method. A ball mill was used for mixing. The ingredientswere therefore 99% Cu and 1 percent (50% Ni-Cu).

The mixture wasdried at 50C to completely remove the alcohol and waspressed into acylinder about 200 mm in length and about 10 mm indiameter by arubber press machine under the pressure of 2,000 kg/cm Thecylinder was sintered in vacuum for 30 .minutes at 700C, and thereafterdrawn by a swaging machine into a wire about 4 mm in diameter. The wirewas annealed at 600C for a few times in order to prevent the hardeningin a continuous drawing step by which the wire was finally drawn to awire 0.7 mm indiameter. The wire was annealed for one hour at 600C. Theadded NiCu was uniformly dispersed in Cu matrix.

The electrical properties were measured in vacuum- (1 X 10" torr.) andat a speed of 0.625C/minute by an automatic electrical resistivitymeasuring equipment, and shown in Table 6.

Table ,6 Continued P/ )3u ratio resistivity :30 to dp/dT (uQcm) (Xl0/C)l0 of pure #Q'cm/C) copper(%) 0.57: (Ni-Cu) -Cu L87 3.06 5.72 84.5 1.0%(Ni-Cu) -Cu L98 2.82 5.58 82.4

Remarks: (Ni Cu) is 50% Ni-Cu alloy.

EXAMPLE 6 The inner and outer conductors of the coaxial cable were madeof copper having 0.15 percent of'Al O dispersed therein, and theinsulator was polyethylene with a low density for submarine cables. FIG.9 shows the changes of attenuation with temperature of 1 kilometersubmarine cables of the type described and 1 inch, 1.5 inch and 2 inchin diameter (curves a, b and c, respectively) in comparison with those(curves a,b, and c) of the conventional submarine, cables of 1 inch, 1.5inch and 2 inch in diameter and using the ordinary soft copper wires. Itis seen that the change of attenuation of the submarine coaxial cable ofthe present invention is reduced to about Vs as compared with theconventional submarine cables. I

What is claimed is:

1. A submarine coaxial cable characterized by comprising I a. an innerconductor,-

b. an outer conductor disposed coaxially of said inner conductor and inspaced apart relation therewith to surround the same,

c. an insulating material filling the space between said inner and outerconductors, and

d. said inner conductor being made of a dispersion type conductivematerial having a temperature coefficient of resistivity lower than thatof pure copper and consisting of copper and 0.01-5.00 percent by weightof finely divided powder dispersed in said copper, said finely dividedpowder being from the group consisting of metal oxides, ferrite,thermistor, carbides, and nickel-copper alloy powder.

2. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of copper having 0.01 5.00percent by weight of finely divided ferrite powder dispersed therein,said ferrite powder being'selected from the group consisting of MnC0Fe OBaFe O NiZnFe O NiCuFe O and ms as m 3. A submarine coaxial cable asdefined in claim 1 wherein said dispersion-type conductive materialconsists of pure copper having dispersed therein 0.01-5.00 percent byweight of finely divided thermistor powder, said thermistor powderconsisting of, as a major component, oxides of transient elementsselected from the group consisting of oxides of Mn, Ni, Co and Cu and,as a minor component, oxides selected from the group consisting of Mo,Fe, Zr, Cr and V. v

4. A submarine coaxialcable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed 0.01 5.00 percent by weight of at least one compound selectedfrom the oxide group consisting of MgO, MnO CrO V 0 and A1203.

5. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01 5.00 percent by weight of at least one compoundselected from the carbide group consisting of TiC, MoC, SiC, TaC, WC andFe C.

6. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01 5.00 percent by weight of 30 percent NiCu alloy(by weight percent).

7. A submarine coaxial cable characterized by comprising a. an innerconductor b. an outer conductor disposed coaxially of said innerconductor and in spaced apart relation therewith to surround the same,

c. an insulating material filling the space between said inner and'outer conductors, and

(1. said inner and outer conductors being made of a dispersion typeconductive material having a temperature coefficient of resistivitylower than th at of pure copper and consisting of copperand 0.01 5.00percent by weight of a finely divided powder dispersed in said copper,said finely divided powder being from the group consisting of metaloxides, ferrite, thermistor, carbides, and nickel-copper alloy powder. 7

8. A submarine coaxial cable as defined in claim 7, wherein saiddispersion-type conductive material consists of copper having 0.01-5.00percent by weight of finely divided ferrite powder disposed therein,said fer rite powder being selected from the group consisting of MnCoFeO BaFe O NiZnFe O,, NiCuFe- O and 0.5 2.5 4'

9. A submarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00

percent by weight of finely divided thermistor powder,

said thermistor powder consisting of, as a-majorcomponent, oxides oftransient elements selected from the group consisting of oxides of Mn,Ni, Co and Cu, and, as a minor component, oxides selected from the groupconsisting of Mo, Fe, Zr, Cr and V.

10. A submarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed 0.01-5.00 percent by weight of at least one compound selectedfrom the oxide group consisting of MgO, MnO CrO V 0 and A1 0 11. Asubmarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of at least one compoundselected from the carbide group consisting of TiC, MoC. SiC. TaC, WC andFe C.

12. A submarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of 30 70 percent NiCualloy (by weight percent).

1. A SUBMARINE COAXIAL CABLE CHARACTERIZED BY COMPRISING A. AN INNERCONDUCTOR, B. AN OUTER CONDUCTOR DISPOSED COAXIALLY OF SAID INNERCONDUCTOR AND IN SPACED APART RELATION THEREWITH TO SURROUND THE SAME,C. AN INSULATING MATERIAL FILLING THE SPACE BETWEEN SAID INNER AND OUTERCONDUCTOR, AND D. SAID INNER CONDUCTOR BEING MADE OF A DISPERSION TYPECONDUCTIVE MATERIAL HAVING A TEMPERATURE COEFFICIENT OF RESISTIVITYLOWER THAN THAT OF PURE COPPER AND CONSISTING OF COPPER AND 0.01-5.00PERCENT BY WEIGHT OF FINELY DIVIDED POWDER DISPERSED IN SAID COPPER,SAID FINELY DIVIDED POWDER BEING FROM THE GROUP CONSISTING OF MATERIALOXIDES, FERRITE, THERMISTOR, CARBIDES, AND NICKEL-COPPER ALLOY POWDER.2. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of copper having 0.01 -5.00 percent by weight of finely divided ferrite powder dispersedtherein, said ferrite powder being selected from the group consisting ofMnCoFe2O4, BaFe12O19, NiZnFe2O4, NiCuFe2O4 and Li0.5Fe2.5O4.
 3. Asubmarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of finely dividedthermistor powder, said thermistor powder consisting of, as a majorcomponent, oxides of transient elements selected from the groupconsisting of oxides of Mn, Ni, Co and Cu and, as a minor component,oxides selected from the group consisting of Mo, Fe, Zr, Cr and V.
 4. Asubmarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed 0.01 - 5.00 percent by weight of at least one compoundselected from the oxide group consisting of MgO, MnO2, CrO2, V2O3 andAl2O3.
 5. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01 - 5.00 percent by weight of at least one compoundselected from the carbide group consisting of TiC, MoC, SiC, TaC, WC andFe3C.
 6. A submarine coaxial cable as defined in claim 1 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01 - 5.00 percent by weight of 30 - 70 percent Ni-Cualloy (by weight percent).
 7. A submarine coaxial cable characterized bycomprising a. an inner conductor b. an outer conductor disposedcoaxially of said inner conductor and in spaced apart relation therewithto surround the same, c. an insulating material filling the spacebetween said inner and outer conductors, and d. said inner and outerconductors being made of a dispersion type conductive material having atemperature coefficient of resistivity lower than that of pure copperand consisting of copper and 0.01 - 5.00 percent by weight of a finelydivided powder disperSed in said copper, said finely divided powderbeing from the group consisting of metal oxides, ferrite, thermistor,carbides, and nickel-copper alloy powder.
 8. A submarine coaxial cableas defined in claim 7, wherein said dispersion-type conductive materialconsists of copper having 0.01-5.00 percent by weight of finely dividedferrite powder disposed therein, said ferrite powder being selected fromthe group consisting of MnCoFe2O4, BaFe12O19, NiZnFe2O4, NiCuFe2O4 andLi0.5Fe2.5O4.
 9. A submarine coaxial cable as defined in claim 7 whereinsaid dispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of finely dividedthermistor powder, said thermistor powder consisting of, as a majorcomponent, oxides of transient elements selected from the groupconsisting of oxides of Mn, Ni, Co and Cu, and, as a minor component,oxides selected from the group consisting of Mo, Fe, Zr, Cr and V.
 10. Asubmarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed 0.01-5.00 percent by weight of at least one compound selectedfrom the oxide group consisting of MgO, MnO2, CrO2, V2O3 and Al2O3. 11.A submarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of at least one compoundselected from the carbide group consisting of TiC, MoC, SiC, TaC, WC andFe3C.
 12. A submarine coaxial cable as defined in claim 7 wherein saiddispersion-type conductive material consists of pure copper havingdispersed therein 0.01-5.00 percent by weight of 30 - 70 percent Ni-Cualloy (by weight percent).